True Position of Slot on OD

[[Ba...]]

Hi all, newer to programing and having trouble with this callout for true position (see mark up). The slot walls are measured as plane feature, A is face plane, B is ID, C (shown in attached) is a slot plane. Every time I attempt I receive an error, sure I am missing a step?
I changed the plane feature representation to angle/not position, with nominal entered.

[[To...]]

What I might do is to create an alignment at the angle of the center of the slot. Then, use CAD > Pre-assignment for new features and pick the newly created alignment. Leave this window open and create a Symmetry Point (probe 2 points, one on each side of the slot). This feature will use the secondary alignment and keep the points normal to the primary axis of the alignment. You may need to adjust the Clearance distance to 0.0 and the Retract Distance to (Slot Width - Probe Diameter)/2. This formula points the stylus at the center of the slot. Then you can create a Position of the Symmetry point. I know I haven't detailed everything to the standard but it's a place to start.